TEST YOUR KNOWLEDGE: Eye series

Dry eyes Eye series 3

Chris Hodge, BAppsc, DOBA, is Research Director, The Eye Institute, Chatswood, New South Wales. Gerard Sutton, MBBS, FRANZCO, FRACS, is a Corneal, Laser Refractive and Surgeon, The Eye Institute, Chatswood, New South Wales.

During her regular check-up a 68 year old woman patient mentions, as an aside, that the recent hot weather has left her eyes with a ‘dry, gritty feeling’. The feeling is more noticeable toward the end of the day and on further questioning has gradually become more prominent over the past few years.

Question 1 Answers Describe the components of the tear film Answer 1 Answer 2 and their respective function. The tear film is composed of three sepa- Dry eyes generally result from a defi- Question 2 rate layers, each with a specific function ciency or compromise to the quality or What are the factors that contribute to (Figure 1). The outer layer is an oily or quantity of the above three layers. dry eyes? lipid layer that primarily serves to reduce Factors that may influence this include: evaporation of the remaining tear film. • age Question 3 The oils are released from the meibomian • medication What clinical signs may suggest dry eyes? glands located on the margins. The • inflammation of the or skin middle or aqueous layer provides mois- • systemic disease Question 4 ture as well as supplying oxygen and • localised irritation or irregularities of What follow up investigations should be nutrients to the . Comprised almost the ocular surface, and conducted? entirely of water, the aqueous layer is pro- • previous eye surgery. duced by the lacrimal gland located under Almost 75% of the population over 65 Question 5 the upper eyelid. This middle layer also years of age will experience dry eye symp- What are the treatment options? carries antibodies and other immune toms. As we age decreased production of defence agents to guard against infection. the aqueous occurs, similarly the body The innermost layer is the mucous (or produces less oil as we grow older. More mucin) layer. Produced by goblet cells, its pronounced in women, this oil deficiency main purpose is to allow the tear film to allows the tear film to evaporate more adhere to the surface and spread evenly. quickly leading to further irritation. Many medications can impair lacrimal gland function leading to dry eyes. These include antibiotics, antihistamines, diuret- ics, oral contraceptives and antianxiety medications. is an inflammation of the oil glands of the eyelids (Figure 2). As the oil

Figure 1. Tear film layers glands become blocked the essential oils

Reprinted from Australian Family Physician Vol. 32, No. 4, April 2003 • 1 n Dry eyes are reduced allowing the tear film to Corneal or refractive surgery can lead any excess crusting will also help. evaporate more quickly. Common signs to short to midterm decrease in the sensi- Inverted or untoward , if are redness of the and lids and tivity of the corneal nerves. As a result, present, should be removed. crusting of the eyelashes. In blepharitis tearing will be reduced until nerve func- With an aqueous deficiency, ie. low tear the symptoms are generally worse in the tion returns. production from the lacrimal gland the morning and improve over the day. first step is introducing artificial tears. Answer 3 Depending on the severity, nonpreserva- More often than not patients with dry tive tears may be prescribed from an eyes syndrome will be more symptomatic hourly to an ‘as necessary’ basis. A lubri- than their respective clinical signs. Unless cating ointment at night will provide inflammation is present the eye will be further relief from symptoms if the condi- mostly white and relatively quiet. If the tion is severe. The patient should be ocular surface is damaged, the continuous warned that when using ointment the eyes irritation can lead to excess tearing in will be sticky upon waking. Ointment may some patients. As this also may be due to also cause a slight, temporary blur to the Figure 2. Blepharitis abnormalities of the lacrimal drainage vision. If a patient does not find relief from Collagen vascular disorders such as system an ophthalmologist should always drops, or does not adhere to treatment, rheumatoid arthritis, lupus and Sjogren’s be consulted. more permanent procedures may be nec- syndrome have a high association with dry essary. Occlusion of the punctum (by small eyes. These inflammatory disorders lead Answer 4 collagen or silicon plugs) will stop the flow to a destruction of the lacrimal gland and Further tests to measure the amount of of tears away from the surface and form a therefore decreased production of the tear tears produced (Schirmer’s tear test) and reservoir to aid lubrication. If successful film. Surgery and radiation may also cause assess the quality of the tear film (tear this option can be made more permanent damage to these glands. Thyroid changes film break up time) will provide further by cauterisation of the punctum. are also associated with dry eyes. evidence to the presence of dry eyes. Nonsurgical options such as increased Results show a decrease in tear produc- hydration through drinking more water tion compared to the average person. and wrap-around sunglasses to avoid When the quality of the tear film is com- excessive wind or UV damage should be promised the tear film will look patchy suggested. Humidifiers at home during and break up quickly after the patient has unusually hot weather may also provide blinked. Staining with dye (Flouroscein or some external relief. Rose Bengal) can exaggerate any defects under microscopic examination and will Further reading help determine the origin of the condition. 1. Stern M, Fox R, Plugfelder s. The pathol- ogy of dry eye: The interaction between ocular surface and lacrimal glands. Cornea Figure 3. Band keratopathy Answer 5 1998; 17(6):584–589. Localised irritation or irregularities will The patient needs to be educated that dry 2. Albietz J M. Dry eye: an update on clinical diagnosis, management and promising cause a disruption to the proper action of eye conditions cannot usually be com- new treatments. Clin Exp Optom 2001; the tear film. growth, corneal pletely cured. Therapy aims to provide 84(1):4–18. scarring and various lid anomalies such as relief of the symptoms and reduce any 3. Huang F C, Tseng S H, Shin M H, Chen F K. Effect of artificial tears on corneal band keratopathy can upset the environ- discomfort. A problem with the eyelids, surface regularity, contrast sensitivity and ment of the eye and lead to symptoms of dry eg. meibomian gland dysfunction (MGD), glare disability in dry eyes. eyes. Band keratopathy (Figure 3) occurs as blepharitis or other lid disease lends itself 2002; 109(10):1934–1940. a result of inadequate blink. The resulting to a therapeutic solution, ie. rapid tear 4. Plugfelder S G, Soloman A, Stern M E. The diagnosis of dry eye: a 25 year review. irritation will leave the patient requiring break up because the oily layer is not of Cornea 2000; 19(5):644–649. constant lubrication to alleviate symptoms. high enough quality to stabilise the tear 5. Korb D R. Survey of preferred tests for Contact lenses can produce irritation film. The underlying cause should be diagnosis of the tear film and dry eye. Cornea 2000; 19(4):483–486. through the rubbing action on the cornea. treated. MGD should be treated with 6. Nichols K K, Begley C G, Caffery B, Jones Some contact brands will also absorb minocycline tablets. Blepharitis may be L A. Symptoms of ocular irritation in a large amount of the tear film further treated with a combination of antibiotic patients diagnosed with dry eye. Optom Vis Science 1999;76(12):838–844. aggravating symptoms. or steroid drops. Lid scrubs to remove AFP

2 • Reprinted from Australian Family Physician Vol. 32, No. 4, April 2003